In shipping transport, there is a major imbalance between net import and net export regions which means that many shipping vessels travel with empty containers. The bibliography consulted, indicates that these percentages could oscillate between 20% and 30% of the world's container transport on the sea. This fact leads to major economic losses for the sector and an environmental problem of astronomical proportions. A collapsible container could be a good solution to this problem. This solution could affect container shipping transport, but also highway and railway transport.
The state of the art features different collapsible container systems, although as described in this document, there are some obstacles for manufacturing and marketing them because of their complexity or as a result of the collapsible design itself which means accessibility to or space within the container is lost.
The U.S. Pat. No. 3,799,384, Collapsible shipping container with application date 28 Feb. 1972 describes a collapsible transport container that has a lower edge of a side wall pivoting on one side of the base with the upper edge of the same side wall fixed to the upper part of a roller assembly, and the upper edge of the other wall pivoting on the other side of the upper part with the lower edge of the same side wall secured to the base by another assembly of rollers.
The roller assembly on the guide permits the upper edge of the side wall to move laterally one way, while the other set of rollers permits the lower edge of the other side wall to move laterally on the base in the opposite direction.
The opposing movements guided by the upper edge of one side wall and the lower edge of the other side wall permit the upper part to move downwards towards the base, while the collapsible transport container is being folded down.
Nevertheless the aforementioned patent U.S. Pat. No. 3,799,384 does not provide a satisfactory solution for different aspects:                The proposed joint and guide system is only compatible with side walls and doors smaller than the standard for conventional ISO containers.        In order for excentric turning to take place with regards the plane of the side walls, the turning point is moved through a catch towards the inside of the container (identified in the document as Number 41) which, when the doors are open, is an obstacle that occupies useful space and hinders entrance to the container, which could lead to incidents during loading/unloading with the subsequent problem of damages to the folding/unfolding system, or a loss of useful capacity in the storage space. This obstacle invades the useful load space, and obviously this circumstance is not true in the case of conventional ISO containers.        The collapsible system is only compatible with one single door which opens to one side only (identified in the document as Number 104), while conventional ISO containers comprise two doors which open to both sides, each one accounting for half the width of the container opening outwards.        The existence of one single door opening to one side is due to the need for the collapsible axis to be fitted to one of the side walls in a position that does not coincide with the joint between the wall and the floor, forcing the solution identified in the document under Number 23.        The door opening inwards is necessary so that the folding of the container can take place without collisions between the different parts.        It is a collapsible system that is only compatible with double folding hinged doors that allow opening of the container outwards, but also opening inwards to allow the folding mechanism to take place. The doors on standard ISO containers only open outwards. The double doors make construction of containers more expensive and jeopardise correct maintenance thereof.        It is not clear how the position of the dead point is overcome before starting the folding action, and if any manual intervention by a person is required to overcome it. The folding movement can apparently not be initiated automatically with the vertical movement of the roof towards the base.        Closing and sealing of the door is complicated since, owing to the fact that the door has to turn inwards to the container, the conventional stepped frames between the floor and the doors cannot be made that guarantee a seal. Double lip seals must be fitted to the door, which complicate maintenance significantly with movement of the container doors in both directions.        
These aspects mean that this technological innovation, in spite of featuring a more simple folding/unfolding movement than other collapsible container options, has not had any technological repercussions in the market, making it a successfully marketed product in the logistics chain.
The container comprising the object of this invention is easy to convert from the usable position, where all the side walls are vertical and the roof rests over them, to a folded position where the side walls and roof lie over the floor, with the aforementioned impediments or restrictions being eliminated.
The patent GB2353275A, Collapsible container body with application date 19 Aug. 1999, reproduces the folding/unfolding movement of the U.S. Pat. No. 3,799,384, but with a securing and turning system at the joint areas that invade the outer limits of the container itself, which is entirely intolerable in the concept of standard ISO containers, where the standardisation rules, mainly in terms of standard measurements, are extremely rigid. Another patent that proposes a solution for folding down containers is US patent 20100018967, Folding container with PCT application date 28 Feb. 2007, although this patent features roll-up doors, which to our understanding are completely incompatible with the folding system and the watertight requirements of shipping containers to be included in the logistics chain. These items completely invalidate it as a folding container solution for implementation.
The technological innovation this invention comprising the object of this patent represents makes it possible to adopt folding/unfolding movement via a combination of turn and slide of the side walls as in the three patents mentioned previously, but resolving the problematic aspects of said patents mainly in terms of the solution to the container doors, since this makes the folding/unfolding movement compatible with the door solution in conventional containers.
Other more recent patents such as WO2008114273, A folding/unfolding transport container and a method of folding and unfolding a transport container, with priority date 21 Mar. 2007, patent EP 2036835, Foldable container with application date 13 Sep. 2007, the American patent US 20110284533, Stackable and collapsible container, with application date 2 Sep. 2012, or the European patent EP 2132111, An apparatus and method for folding and unfolding a foldable transport container with application date 17 Mar. 2008 propose folding containers with different folding mechanisms, emphasising the interest there is in the sector to find a container that can be folded.
The state of the art does not contemplate a technical solution such as the one described in this patent, which takes different aspects considered suitable to attain compliance with the expectations of the sector.